1. Field of the invention
The present invention relates to a positive-tone or negative-tone radiation sensitive resin composition which contains a specific photoacid generator and is useful as a resist suitable for use in precision machining utilizing various types of radiation such as ultraviolet light, deep ultraviolet light, X-rays, or charged particle rays.
2. Description of the Background Art
There is an increasing demand for miniaturization, requiring reduced processing sizes in lithography, in fields requiring fine work such as manufacture of integrated circuits (ICs) in order to achieve high integrity in ICs. Technologies capable of fine processing, even of a size of 0.5 mm or smaller, in a stable manner have become necessary in recent years. Because of this, resists used in such a technology must be capable of forming patterns smaller than 0.5 mm at high precision. It is extremely difficult to produce a minute pattern smaller than 0.5 mm at a high precision by conventional methods using visible light (wavelength 800-400 nm) or near ultraviolet light (wavelength 400-300 nm). Because of this, the use of short wavelength radiation (wavelength 300 nm or less) has been studied.
Given as examples of such a short wavelength radiation are deep ultraviolet rays, such as a bright line spectrum of a mercury lamp (wavelength 254 nm), a KrF excimer laser (wavelength 248 nm), and an ArF excimer laser (wavelength 193 nm); X-rays such as synchrotron radiation; and charged particle rays such as an electron beam. Lithography using an excimer laser among these is attracting a great attention due to its high output and high efficiency. For this reason, the resists used in lithography also must produce minute patterns of 0.5 mm or less with high sensitivity and high resolution by excimer laser with good reproducibility.
A chemically amplified resist using a radiation sensitive acid generator which generates an acid by being exposed to radiation (hereinafter referred to as "exposure") and in which the sensitivity of resist is increased by the catalytic action of the acid has been proposed as a resist applicable for use with deep ultraviolet light such as from an excimer laser.
As examples of such chemically amplified resists, a combination of a resin protected by a t-butyl group or t-butoxy carbonyl group and a photoacid generator is disclosed in Japanese Patent Application Laid-open No. 45439/1984. Japanese Patent Application Laid-open No. 52845/1985 discloses a combination of a resin protected by a silyl group and a photoacid generator. Beside these, there are many reports relating to chemically amplified resists such as, for example, a resist which contains a resin having an acetal group and a photoacid generator (Japanese Patent Application Laid-open No. 25850/1990).
Given as examples of the photoacid generator used in these chemically amplified resists are onium salts, such as triphenylsulfonium trifluoromethanesulfonate, triphenylsulfonium hexafluoroantimonate, triphenylsulfonium naphthalenesulfonate, cyclohexylmethyl(2-oxocyclohexyl) sulfonium trifluoromethanesulfonate; sulfonate of 2,6-dinitrobenzyl, tris(methanesulfonyloxy)benzene, and bis(cyclohexylsulfonyl)diazomethane. These conventional photoacid generators are generally unsatisfactory in their sensitivity. Some photoacid generators have relatively high sensitivity, but their overall resist performance, such as resolution and pattern configuration, is not necessarily sufficient.
In view of this situation, there has been a strong desire for the development of a photoacid generator exhibiting high sensitivity and high resolution, and capable of producing fine pattern configuration.
An object of the present invention is therefore to provide a positive tone or negative tone radiation sensitive resin composition capable of producing a superior resist pattern with high sensitivity, high resolution, excellent pattern configuration.